Field of the Invention
The invention relates to a method of manufacturing a semiconductor device and more particularly, to methods of manufacturing a memory device.
Description of Related Art
A dynamic random access memory (DRAM) is a volatile memory formed by a plurality of memory cells. Each of the memory cells is mainly composed of a transistor and a capacitor controlled by the transistor, and the memory cells are electrically connected with one another through word lines and bit lines. In order to improve the integration of DRAM to increase the operating speed of the device and to meet the consumers' demand for miniaturization of electronic devices, buried word line DRAM has been developed in recent years for the aforementioned purposes.
With development of technology, electronic products are developed to have design features of lightness, slimness, shortness and smallness. In this case, the critical dimension of the DRAM is also reduced, which result in many challenges for the DRAM process.